The snow had receded from all but the mountain tops in the western United States when the <a href="http://modis.gsfc.nasa.gov" target="outlink">Moderate Resolution Imaging Spectroradiometer</a> (MODIS) on NASA’s <a href="http://aqua.nasa.gov/" target="outlink"> Aqua</a> satellite captured this remarkably cloud-free image on April 25, 2004. The snow highlights the topography of the west, showing the line of the Cascade and Sierra Nevada Mountain Ranges down the west coast. The Rocky Mountains can be seen curving out of the image to the southeast through western Montana and central Idaho. Sandwiched between the two great mountain ranges is the Great Basin Desert, a vast high desert that covers Nevada, southeastern Oregon, southern Idaho, western Utah, and a slice of southern California. It is the largest desert in the United States, covering about 190,000 square miles, and grows larger as geologic forces pull the Sierra Nevada away from the Rockies. Tucked behind the rain shadow of the Sierra Nevada, the desert is covered by low-growing sagebrush, and appears mostly tan in this true-color image. The states shown in this image include, clockwise from the top left, Washington, Idaho, Montana, Utah, Arizona, Nevada, California, and Oregon. Sensor: Aqua/MODIS. Data Start Date: 4/25/04.